Slit seal and multiple tube gusseter



Nov. 10, 1964 v, OSBORN, JR 3,156,010

SLIT SEAL AND MULTIPLE TUBE GUSSETER Filed May 10, 1965 PAUL V. OSBORN,Jr.

INVENTOR.

United States Patent 3,156,010 SLIT SEAL AND MULTIPLE TUBE GUSSETER Paul Victor Qsborn, .l'rz, Rochester, N.Y., assignor to National Distillers and Chemical Corporation, New York, N.Y., a corporation of Virginia Filed May 10, 1963, Ser. No. 279,364 3 Claims. (Cl. 18-14) This invention relates to a novel system for the production of tubes of thin gauge thermoplastics, and more specifically relates to a novel system which is directly adjustable between production of a single tube to produc tion of a plurality of tubes without requiring rethreading of the equipment.

In producing tubes of thermoplastic materials such as tubes of polyethylene, the tube is normally drawn from a circular die and through a pair of nip rolls which flatten the tube after it has appropriately cooled. Thereafter, the tube may be reinflated and taken through gusseting means and thence to an appropriate cutter which can form the gusseted tube into gusseted bags.

If it is desired to draw two small diameter tubes through a line which is adapted for a large diameter single tube, the common practice as been to provide a special dual die arrangement, or to otherwise provide for the flow of the two parallel tubes through the same equipment by rethreading the tubes through the equipment.

The principle of the present invention is to provide novel auxiliary equipment which permits the direct change-over from single tube gusseting to double tube gusseting or vice versa without rethreading the line in any way.

More specifically, in accordance with the invention, a slit sealer is movable into engagement with the drawn tube as it leaves the first nip rolls to slit the tube and simultaneously seal the ends of the slit tube. This provides two parallel running tubes. The two tubes are then taken over adjustable rollers which operate to separate the paths of the slit tubes, whereupon the two slit tubes are taken through respective gusseter stations where the two tubes are independently gusseted. The two tubes are thereafter carried parallel to one another to appropiate bag making machinery.

Accordingly, a primary object of this invention is to provide a novel structure for changing between single and double gusseted tube operation without rethreading the equipment.

Another object of this invention is to provide a novel arrangement to permit the operation of an in-line system to be changed from single to double operation and back from double to single operation at will.

A further object of this invention is to decrease the occurrence of shut-down of a line due to air loss in a tube during dual tube extrusion.

These and other objects of this invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 schematically illustrates a perspective view of the novel system of the invention when adjusted for dual tube operation.

FIGURE 2 illustrates the adjusted roll position for single tube operation.

FIGURE 3 shows a cross-sectional view of the gusseted bag.

Referring now to the figures and specifically to FIGURE 1, I have illustrated therein a known single tube extruding die 10, which is fed from the source of molten thermoplastic material 11, which is under high pressure. The die 11 extrudes a tube 12 of thermoplastic material and inject air into extruded tube to keep it inflated.

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Appropriate cooling means such as air rings (not shown) surround the tube to solidify the molten material. A pair of nip rolls 13 and 14 grasp the upper portion of the tube and flatten it, and are appropriately driven to continue to move the tube out of extrusion die 11.

The flattened tube is then carried over a roller 15 and directed along a path which includes a cutter and sealer structure 16. More specifically, the cutter and sealer structure 16 is pivotally mounted on a pivot 17, and is essentially comprised of an appropriate electrically heated wire 18 which can be moved into engagement with the flattened web coming over roller 15. The heated wire 18 is of a well-known type and serves to both slit and seal the slit edges of the web as it moves past the wire.

The heated wire 18 comes to an operative position by providing appropriate stop means and, in accordance with the invention, can be rotated in a counterclockwise direction about pivot point 17 to an inactive position by any desired type of mechanism, whereupon the web would continue as a single web.

Assuming, however, that the hot wire 18 is in the operative position shown in FIGURE 1, it will be understood that the web is continually sliced into two webs and the slit edges of the two webs 20 and 21 are sealed so' that the two webs are formed into individual tubes.

The two webs 20 and 21 are then passed over a roll 22 and under a roll 23 toward left pivoting rolls 24 and 25 and right pivoting rolls 26 and 27 respectively. Rolls 24 and 25 are parallel to one another and are mounted in a common frame (not shown). The frame is pivotally mounted in such a manner that rolls 24 and 25 will pivot about the axis 28 which is above the rolls 24 and 2S and is perpendicular to the plane of rolls 24 and 25. Thus rolls 24 and 25 are rotatable from the unslit web operating position of FIGURE 2 to the slit web operating position of FIGURE 1.

Rolls 26 and 27 are supported in a manner identical to that of rolls 24 and 25, whereby rolls 26 and 27 are pivotable about axis 29 to be movable between the positions shown in FIGURES l and 2. Note that rolls 24 and 25 are coaxial with rolls 26 and 27 respectively in the position of FIGURE 2.

The web, whether slit or unsilt, then passes over roll 30.

Assuming that two webs are formed as in FIGURE 1, the webs are inflated in the usuall manner and are then individually received by appropriate gusseting plates 37 and 38 for tube 20 and gusseting plates 39 and 40 for tube 21.

After gusseting, the two tubes are brought through the nip rolls 41 and 42, and are then moved outwardly and toward an appropriate roll or bag making machine. The form of the gusseted web leaving nip rolls 41 and 42 is that shown in FIGURE 3.

Where it is now desired to make a single gusseted bag, the position gusseting plates 37 through 40 is adjusted so that plates 37 and 38 will operate on the single tube. Rolls 24 through 27 are then rotated back toward their position of FIGURE 2, which operation will bring the adjacent sides of webs 20 and 21 together. Thereafter, the heated knife 18 is raised so that a single tube will now pass over roller 30 and through nip rolls 41 and 42. Finally, gusseting plates 37 and 38 are brought into the opposing sides of the single tube to gusset this single tube.

To prevent the possibility of the tube catching on the gusseting plates 39 and 40 during transition from double to single tube operation, a camming plate 43 is movable to a position between plates 38 and 39 to guide one side of the single web toward gusseter plate 38.

If it is now desired to return to the two-tube operation, it is clearly only necessary to reverse the above operation whereby it can be seen that the line can go from single to double tube operation without the requirement of rethreading anywhere in the system.

An important advantage of the invention during dual operation is in prevention of shutdown if there is air loss in one of the tubes. That is, one of the hazards of in-line operation with an extruder is air loss in the tube being extruded which gives a much smaller tube size. Depending upon the gauge of the film being extruded, occurrence of this can be fairly frequent. If there were a separate web threading pattern on a dual tube operation such losses would undoubtedly mean complete rethreading of the lines, a time consuming process taking between and 15 minutes. However, with the novel multiple tube gusseter of the invention, it is only necessary to go from dual to single tube operation when this occurs and return to the dual operation after the steady state has been resumed in the extrusion process. The invention also makes it possible to thread up a line initially on a single tube basis and go to the dual operation only after steady operation has been achieved in the extrusion, printing, winding and/ or bag making area. Although this novel invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be apparent to those skilled in the art, and it is preferred to be limited not by the specific disclosure herein but only by the appended claims.

What is claimed is:

1. A slit seal gusseter comprising, in combination; means for extruding a tubular web of thermoplastic material, nip roll means for flattening said tube, slitting and sealing means for slitting central portions of said web and sealing the ends of each slit half together to form two parallel tubular webs; adjustable roller means for causing said two tubular webs to diverge from one another; said adjustable roller means including a first and second roller; at least one of said first and second rollers being angularly rotatable between a first and second adjustment position; said first and second rollers being coaxial with one another and having their ends in substantially abutting relation when said at least one of said rollers is in its said first adjustment position; the axes of said first and second rollers being at an angle to one another when said at least one of said rollers is in its said second adjustment position to cause said two tubular webs to diverge from one another; and gusseting means for gusseting the sides of each of said two tubular webs; said slitting and sealing means being movable between an operable and non-operable position with respect to said tubular web.

2. The device substantially as set forth in claim 1 wherein said adjustable roller means includes a first and second roller adjustable from a coaxial position when said slitting and sealing means is in said non-operable position to a position wherein the axes of said first and References Cited in the file of this patent UNITED STATES PATENTS 2,805,700 Klasing et al. Sept. 10, 1957 2,961,930 Wamsley et al Nov. 29, 1960 2,995,990 Pierce et al Aug. 15, 1961 FOREIGN PATENTS 816,931 Great Britain July 22, 1959 

1. A SLIT SEAL GUSSETER COMPRISING, IN COMBINATION; MEANS FOR EXTRUDING A TUBULAR WEB OF THERMOPLASTIC MATERIAL, NIP ROLL MEANS FOR FLATTENING SAID TUBE, SLITTING AND SEALING MEANS FOR SLITTING CENTRAL PORTIONS OF SAID WEB AND SEALING THE ENDS OF EACH SLIT HALF TOGETHER TO FORM TWO PARALLEL TUBULAR WEBS; ADJUSTABLE ROLLER MEANS FOR CAUSING SAID TWO TUBULAR WEBS TO DIVERGE FROM ONE ANOTHER; SAID ADJUSTABLE ROLLER MEANS INCLUDING A FIRST AND SECOND ROLLER; AT LEAST ONE OF SAID FIRST AND SECOND ROLLERS BEING ANGULARLY ROTATABLE BETWEEN A FIRST AND SECOND ADJUSTMENT POSITION; SAID FIRST AND SECOND ROLLERS BEING COAXIAL WITH ONE ANOTHER AND HAVING THEIR ENDS IN SUBSTANTIALLY ABUTTING RELATION WHEN SAID AT LEAST ONE OF SAID ROLLERS IS IN ITS SAID FIRST ADJUSTMENT POSITION; THE 